Prepared CrSi₂Film Structure And Electrical Properties Sputtering

The thin CrSi2nanostructure films were prepared on the mirror-polished single crystalSi(100) substrate using the high vacuum magnetron sputtering by alternately depositing Cr andSi layer.The prepared films were annealed in vacuum chamber under the500℃.The thin(Cr,Ti)Si2nanostructure films with different Ti mole fraction by changing the Ti doping molefraction. The thin Cr(Si,Al)2nanostructure films with different Al mole fraction can beprepared by changing the Al doping mole fraction.The microstructure, chemical composition,surface morphology, phase composition，Hall coefficient and electric conductivity of this thinfilm were analyzed and determined.The solid solution of (Cr,Ti)Si2structure forms by Ti atom substituting Cr atom in CrSi2lattice during the variation of the Ti mole fraction from1.02at%to1.74at%. The films withdifferent Ti doping mole fraction have a preferred orientation of (111) plane and the degree ofpreferred orientation of the film reduces with the increase of Ti doping mole fraction.Meantime, the hole carrier concentration in the crystal increases with increasing the Ti molefraction. And the larger lattice distortion and the increase of the internal crystal defects resultin the decrease of the carrier mobility.This causesa maximum of electric conductivity.Therefore, an optimum Ti content is determined by experiments so that the films haveexcellent electrical properties.The phase composition of films changes as increasing doping Al mole fraction.There isonly Cr(Si,Al)2in the films as the Al doping mole fraction is no more than2.40at%. There isCr4Si4Al13phase in the thin film as well as the Cr(Si,Al)2phase as doping Al mole fraction ismore than the11.71at%. When the doping Al mole fraction increases to26.26at%above, thereis not only Cr(Si,Al)2and Cr4Si4Al13phases, but also the existence of metal Al phase in thethin film. For the film with Al mole fraction1.83at%, the grain size in the thin Cr(Si,Al)2filmranges from85nm to174nm with a slight increase in grain sizewhen the annealing time rangefrom2h to8h. The larger lattice distortion caused by Al atoms result in the larger latticeconstant with the increase of the Ti mole fraction. For the films with no more than2.40at%doping Al mole fraction, the carrier concentration in the film increases, the carrier mobilitydecreases and the electrical conductivity shows ascendant trend with increasing doping Al mole fraction.With the extension of the annealing time, the film grain size increased slightly. Becausethe part crystal defects of the films was reset, the hole concentration of films measured by testdecreased. For Ti doping, extending annealing time, the film electric conductivity and holemobility showed a decreasing trend. For doping Al, extending annealing time, the film electricconductivity reduced and the hole mobility increased.